1. Field of the Invention
The present invention relates to an emergency stop releasing method for releasing an emergency stop state of an elevator.
2. Description of the Background
With the increasing construction of high-rise buildings, the operating speed of elevators is becoming higher and higher, thus requiring satisfactory safe measures. A conventional elevator apparatus includes an elevator shaft, extending vertically in a building, and a machine room (penthouse), which is located right over the shaft and stores a motor and the like. This elevator apparatus further includes a sheave located in the machine room and driven by means of the motor, a cage disposed in the shaft and connected to one portion of a cable that is placed around the sheave, and a counterweight connected to another portion of the cable and balanced with the cage. The cage is moved up and down by rotating the sheave by means of the motor in the machine room. The cage and the counterweight are guided by means of guide rails arranged in the elevator shaft.
The elevator apparatus of this type is provided with an emergency stop device that can stop the cage safely and securely in case the cage suddenly descends for any reason at a speed higher than its rated speed. The emergency stop device brakes and stops the cage in a manner such that wedge members, for example, are caught between the cage and the guide rails.
If the emergency stop device is activated, especially when people are confined to the cage, the device should be capable of being urgently released to rescue the people from the cage. In order to release the emergency stop device of this type, the cage must be slightly lifted to allow the wedge members to slip out from between the cage and the guide rails.
In the case of conventional elevators, an operator enters the machine room and manually rotates a motor of a drive unit by means of a handle, thereby gradually lifting the cage to release the emergency stop device.
If the machine room, which stores various devices including the drive unit, control device, etc., is located over the elevator shaft, as mentioned before, however, it projects above the rooftop of the building, for example, possibly resulting in blocking access to sunshine. Recently, therefore, a machine-room-less elevator has become the object of attention in the art. In the elevator of this type, no machine room is located over the elevator shaft, and a small-sized drive unit instead is provided in a narrow space in the upper or middle part of the shaft.
In the case of the elevator having the drive unit arranged in this manner, however, the emergency stop device cannot be released with ease once it is activated. Since the drive unit is located in a narrow space in the elevator shaft, the operator cannot enter the space and manually actuate the drive unit. Thus, it is very difficult to release the emergency stop device.